Please recommend me some Manual Focus EF lenses!

[kye]

2 hours ago, maxJ4380 said:

I was going to suggest one of those friction clothes, mum has a few in the kitchen drawer for hard to open jam jars. If that didn't work, one drop of wd-40 on the threading left to  sit over night, only one drop mind you as you dont want to find out that wd-40 might be also good at delaminating glass elements

It actually feels like it's in a softer set of threads, so it's not like metal on metal where it grips and then slides easily, this just requires a certain level of force to get it to move and once moving it requires the same force to keep it moving.

I would absolutely never ever put something like WD-40 into an optical assembly!  Not only would it potentially dissolve or melt any plastic it comes into contact with, but solvents can 'wick' into things and spread across surfaces (especially bad if those surfaces are on the inside and you can't get at them to clean them), and solvents will evaporate and likely fill every void or space with fumes, which can potentially condense on the surfaces of the lenses and dissolve the coatings etc.

I've glued things together before with PVA glue, which is water based, and after the glue had dried (ie, the water in it evaporated) it had condensation all over the sensor and lens etc.  I set it on a windowsill in the sun to dry for a few days and it cleared up fine, but I think that was mostly because it was water and that didn't interact in any way with the lens or sensor elements.

[eatstoomuchjam]

Famously, the greases that Leica used in their old lenses would evaporate and deposit on lens elements over time.  It can be cleaned, but the danger of evaporation/depositing is real!

[Emanuel]

39 minutes ago, eatstoomuchjam said:

Famously, the greases that Leica used in their old lenses would evaporate and deposit on lens elements over time.  It can be cleaned, but the danger of evaporation/depositing is real!

Not only the Leica :- )